graphics/kealib: Add kealib 1.6.2

KEALib provides an implementation of the GDAL data model. The format supports
raster attribute tables, image pyramids, meta-data and in-built statistics while
also handling very large files and compression throughout.

Based on the HDF5 standard, it also provides a base from which other formats can
be derived and is a good choice for long term data archiving. An independent
software library (libkea) provides complete access to the KEA image format and a
GDAL driver allowing KEA images to be used from any GDAL supported software.